/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.connector.base.source.reader.mocks;

import org.apache.flink.api.connector.source.Boundedness;
import org.apache.flink.api.connector.source.Source;
import org.apache.flink.api.connector.source.SourceReader;
import org.apache.flink.api.connector.source.SourceReaderContext;
import org.apache.flink.api.connector.source.SplitEnumerator;
import org.apache.flink.api.connector.source.SplitEnumeratorContext;
import org.apache.flink.api.connector.source.mocks.MockSourceSplit;
import org.apache.flink.api.connector.source.mocks.MockSourceSplitSerializer;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.connector.base.source.reader.RecordsWithSplitIds;
import org.apache.flink.connector.base.source.reader.SourceReaderOptions;
import org.apache.flink.connector.base.source.reader.synchronization.FutureCompletingBlockingQueue;
import org.apache.flink.core.io.SimpleVersionedSerializer;
import org.apache.flink.util.InstantiationUtil;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A {@link Source} class for unit test of base implementation of source connector.
 */
public class MockBaseSource implements Source<Integer, MockSourceSplit, List<MockSourceSplit>> {
	private static final long serialVersionUID = 4445067705639284175L;

	private final int numSplits;
	private final int numRecordsPerSplit;
	private final int startingValue;
	private final Boundedness boundedness;

	public MockBaseSource(int numSplits, int numRecordsPerSplit, Boundedness boundedness) {
		this(numSplits, numRecordsPerSplit, 0, boundedness);
	}

	public MockBaseSource(int numSplits, int numRecordsPerSplit, int startingValue, Boundedness boundedness) {
		this.numSplits = numSplits;
		this.numRecordsPerSplit = numRecordsPerSplit;
		this.startingValue = startingValue;
		this.boundedness = boundedness;
	}

	@Override
	public Boundedness getBoundedness() {
		return boundedness;
	}

	@Override
	public SourceReader<Integer, MockSourceSplit> createReader(SourceReaderContext readerContext) {
		FutureCompletingBlockingQueue<RecordsWithSplitIds<int[]>> elementsQueue =
				new FutureCompletingBlockingQueue<>();

		Configuration config = new Configuration();
		config.setInteger(SourceReaderOptions.ELEMENT_QUEUE_CAPACITY, 1);
		config.setLong(SourceReaderOptions.SOURCE_READER_CLOSE_TIMEOUT, 30000L);
		return new MockSourceReader(
				elementsQueue,
				() -> new MockSplitReader(2, true),
				config,
				readerContext);
	}

	@Override
	public SplitEnumerator<MockSourceSplit, List<MockSourceSplit>> createEnumerator(
			SplitEnumeratorContext<MockSourceSplit> enumContext) {
		List<MockSourceSplit> splits = new ArrayList<>();
		for (int i = 0; i < numSplits; i++) {
			int endIndex = boundedness == Boundedness.BOUNDED ? numRecordsPerSplit : Integer.MAX_VALUE;
			MockSourceSplit split = new MockSourceSplit(i, 0, endIndex);
			for (int j = 0; j < numRecordsPerSplit; j++) {
				split.addRecord(startingValue + i * numRecordsPerSplit + j);
			}
			splits.add(split);
		}
		return new MockSplitEnumerator(splits, enumContext);
	}

	@Override
	public SplitEnumerator<MockSourceSplit, List<MockSourceSplit>> restoreEnumerator(
			SplitEnumeratorContext<MockSourceSplit> enumContext,
			List<MockSourceSplit> checkpoint) throws IOException {
		return new MockSplitEnumerator(checkpoint, enumContext);
	}

	@Override
	public SimpleVersionedSerializer<MockSourceSplit> getSplitSerializer() {
		return new MockSourceSplitSerializer();
	}

	@Override
	public SimpleVersionedSerializer<List<MockSourceSplit>> getEnumeratorCheckpointSerializer() {
		return new SimpleVersionedSerializer<List<MockSourceSplit>>() {
			@Override
			public int getVersion() {
				return 0;
			}

			@Override
			public byte[] serialize(List<MockSourceSplit> obj) throws IOException {
				return InstantiationUtil.serializeObject(obj.toArray());
			}

			@Override
			public List<MockSourceSplit> deserialize(int version, byte[] serialized) throws IOException {
				MockSourceSplit[] splitArray;
				try {
					splitArray = InstantiationUtil.deserializeObject(serialized, getClass().getClassLoader());
				} catch (ClassNotFoundException e) {
					throw new IOException("Failed to deserialize the source split.");
				}
				return new ArrayList<>(Arrays.asList(splitArray));
			}
		};
	}
}
